1. Field of Invention
The present invention relates to an input device for an electronic device, in particular, to an input device for a multiplex control signal.
2. Related Art
There are generally two types of input devices, namely, touch type and button type used in electronic devices, e.g. personal computers (PC), notebook computers, table PCs, mobile phones, personal digital assistants (PDA), smart phones, navigation devices, or machines with human-machine interfaces.
For a notebook computer, two input devices, i.e., a touchpad and a keyboard, are simultaneously disposed on the current notebook computer, for providing multiple input modes. The user can slide finger on the touchpad, and at this time the movement direction of the finger is the movement direction of the mouse pointer on the liquid crystal display (LCD). The user can input words, numerals, signs through the keyboard. However, the two input devices, i.e. the touchpad and the keyboard are disposed on the notebook computer in a separate manner, thus wasting much space.
Accordingly, for electronic devices in need of small volumes, e.g. table PCs, mobile phones, personal digital assistants (PDA), smart phones, and navigation devices, only one single input device (touchpad or keyboard) is provided. However, in order to achieve multiple functional services, the input operation is very complex.
For an electronic device merely provided with touchpad as an input device, the touchpad must be used together with software or firmware. Moreover, most kinds of touchpad can merely provide click control or control of movement of the mouse pointer. Words/signs must be input though the software (for example, handwriting input software or on-screen keyboard).
However, for electronic devices only provided with the button input function, each button can only provide one signal control. When the execution of different instructions is controlled by a single button, it is necessary to switch the input mode, so as to switch the executive instructions generated by the button. For example, the first button may input numerals or English letters or signs, and the second button may switch the input mode. When the user selects the numeral input mode with the second button, he/she presses the first button to input the corresponding numeral. Similarly, when the user selects the English letter input mode with the second button, he/she presses the first button to input the corresponding English letter. When the user selects the sign input mode with the second button, he/she presses the first button to input the corresponding sign.